Menu Custom link – using relative link when WP is in a subdirectory

/events is not a relative link, it’s an absolute link. The beginning slash forces it to the root of the domain. Of course, a relative link like events will be relative to the current page, so if you’re on a page like this domain.com/dev/something/ it’ll be domain.com/dev/something/events.

If you’re developing a WP site that will eventually live at the root of the domain, I suggest you rethink your development process. Build the site on localhost or a subdomain, so that when you move you don’t have to repoint links, just migrate, fix the DB, and go.